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Cardiac resynchronization therapy: helpful now in selected patients with CHF.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Kereiakes, Dean J. |
| Copyright Year | 2004 |
| Abstract | Drs Leclercq and Hare 1 and Auricchio and Abraham have comprehensively reviewed the state of cardiac resynchronization therapy (CRT). As they emphasize, this novel pacing approach to treat heart failure shortens or optimizes the atrioventricular interval necessary to resynchronize lateral-septal contractions and improves atrioventricular mechanical synchrony by abolishing late diastolic ventriculoatrial gradient and the “presystolic mitral regurgitation” that is often seen with ventricular dyssynchrony. Pacing from the left lateral wall produces early activation of the papillary muscle region and may decrease systolic mitral regurgitation. Relative optimization of ventricular loading conditions as provided by CRT improves myocardial efficiency at no increased oxygen cost and increases systolic function with little effect on diastolic function. In addition to the positive hemodynamic effects mentioned above, CRT reduces sympathetic activity and may induce “reverse remodeling” of the failing left ventricle. With CRT, optimal responders develop smaller left ventricles and contractility is improved in the subsequent days to weeks. The CRT device has more sophisticated software and hardware than standard pacemakers and requires more extensive follow-up visits and, thus, a higher cost. The software allows storage of intracardiac electrograms and monitoring of a patient’s physical activity and heart rates and heart rate variability. It is anticipated in the future that selected respiratory characteristics, body temperature, and body water content might also be possible to obtain with advanced software currently under development. CRT is indicated for selected patients with symptomatic heart failure. These patients should be in a functional New York Heart Association class III, they should have a QRS duration of 130 ms or greater, left ventricular ejection fractions of 35% or less, and left ventricular end-diastolic diameters 55 mm for one to see improvement in symptoms, functional status, and exercise capacity. Evidence from several clinical trials suggests that CRT markedly reduces combined measures of morbidity and probably of mortality when used alone or with a defibrillator. Current recommendations call for the use of optimized pharmacological therapy, including angiotensin-converting enzyme inhibitors, selected -adrenergic blockers, and an aldosterone inhibitor before initiating CRT therapy. There are a number of issues that remain unresolved as regards CRT therapy. First, it is not clear whether dyssynchrony represents a cause or a consequence of heart failure. It seems possible that it may be a marker of progressive cardiac dysfunction. Secondly, there is a paucity of evidence as regards potential long-term clinical benefit from CRT; clinical trials that have been done to date are relatively short, months to 1 year. The ongoing COMPANION and CARE-HF trials will provide longer follow-up evaluations, and the COMPANION trial will also provide information about long-term clinical benefits both of CRT and of CRT with a defibrillator. Thirdly, the efficacy of CRT for the treatment of patients with narrow QRS duration has only recently been explored as more definative measures of detecting asynchrrony evolve. Can earlier application of CRT before ventricular dilatation alter the natural progression of dilated congestive cardiomyopathy? Can left ventricle-only pacing achieve long-term effects similar to those of biventricular |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://circ.ahajournals.org/content/circulationaha/109/3/308.full.pdf?download=true |
| PubMed reference number | 14744955v1 |
| Volume Number | 109 |
| Issue Number | 3 |
| Journal | Circulation |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Aldosterone Antagonists Angiotensin-Converting Enzyme Inhibitors Angiotensins Body Temperature Body water (substance) Cardiac Resynchronization Therapy Cardiomyopathies Cardiomyopathy, Dilated Defibrillators Diastole Dilate procedure Evaluation Exercise Follow-Up Report Heart Diseases Heart Ventricle Heart failure Hemodynamics Left ventricular structure Mitral Valve Insufficiency Morbidity - disease rate Oxygen Patients Pharmacology Regurgitation Small Structure of papillary muscle Ventricular Remodeling benefit heart rate |
| Content Type | Text |
| Resource Type | Article |
